San Francisco’s office and multifamily real estate markets will see a slowdown in rental growth and a downturn starting this year, according to a report by PwC.

PwC projects that San Francisco office rents will decline by an average of 5 percent per year between 2015 and 2018. New office construction will raise supply by around 6 percent, which will lead to excess space that “will put increased downward pressure on rent levels,” said Emily Pillars, partner at PwC.

The PwC report is based on responses from real estate investors and data from commercial real estate brokerages.